Food science and applied nutrition / Kimberly Burgess

FOOD SCIENCE

AND

APPLIED NUTRITION

KIMBERLY BURGESS

FOOD SCIENCE AND

APPLIED NUTRITION

FOOD SCIENCE AND

APPLIED NUTRITION

Kimberly Burgess

Food Science and Applied Nutrition

by Kimberly Burgess

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© 2018 Tritech Digital Media

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Contents

1. Introduction 1

2. Essentials of Basic Nutrition 7

3. Food and Nutrition 21

4. Food Security 99

5. Nutrition: What, When and How to Eat 122

6. Food Safety and Management 136

7. Preservation of Food 175

8. Human Foods, Nutritive Value and Nutrition Labelling 196

1

Introduction

The nutritional status of a population depends on the availability of

food, its consumption, and its biological utilization. A natural disaster may

affect the nutritional status of the population by affecting one or more

components of the food chain depending on the type, duration, and extent

of the disaster, as well as the food and nutritional conditions existing in

the area before the catastrophe. Slow-onset disasters such as drought are

more likely to affect long-term nutritional status than sudden-onset

disasters such as earthquakes and hurricanes. Not all sudden-onset

disasters produce food shortages severe enough to cause harmful changes

in the nutritional status of the population. The effect of any type of disaster

on the nutritional status of the affected population is never immediate.

Largescale food distribution is not always an immediate relief priority,

and its long-term implementation may, in fact, produce undesired effects.

To plan and implement successful food relief operations, nutrition

workers responsible for humanitarian operations must be familiar with

the possible nutritional outcomes of specific types of natural disasters, as

well as the food and nutrition situation in the affected area prior to the

disaster. A nutrition officer trained in emergency management must be

part of the disaster planning and response teams.

The immediate steps for ensuring that a food relief programme will be effective

include:

• Assessing the food supplies available after the disaster;

• Gauging the nutritional needs of the affected population;

2 Food Science and Applied Nutrition

• Calculating daily food rations and needs for large population

groups; and

• Monitoring the nutritional status of the affected population.

EXPECTED CONSEQUENCES OF

DISASTERS ON THE FOOD CHAIN

Hurricanes, floods, land- or mudslides, volcanic eruptions, and sea

surges directly affect food availability. Standing crops may be completely

destroyed, and seed stores and family food stocks may be lost, especially

if there is no warning period. Volcanic eruptions can cause widespread

crop destruction: food crops may be burned, defoliated, and buried under

ashfall; reduced photosynthesis resulting from ash clouds limits

subsequent production.

Earthquakes, on the other hand, generally have little direct impact on

the longterm total availability of food. Standing crops are unaffected, and

food stocks can often be salvaged from family, wholesale, and retail stores.

However, temporary food problems may result as a consequence of the

breakdown of the transportation and marketing systems. If an earthquake

strikes during a labour-intensive period such as harvest, the loss of labour

from death or its diversion from agriculture may cause short-term

scarcities.

The most likely consequence of any kind of sudden-impact disaster

will be the disruption of transportation and communications systems and

upheavals in routine social and economic activities. Even when food stocks

exist, they may be inaccessible due to disruptions in the distribution system

or the loss of income with which to buy food.

Destruction of cash crops also will have an effect on the economy of

families. When destruction of a greater magnitude occurs, leading to the

death of livestock and the loss of crops and stored foodstuffs, the short￾term dilemma can leave a more severe, long-term crisis in its wake.

Moreover, evacuation and resettlement of communities during the

post-disaster period are often necessary, creating foci in which total food

supplies will have to be provided for the duration of the encampment.

Hospitals and other institutions may require emergency food supplies as

well. Livestock may have to be sacrificed if they cannot be fed, and they

are likely to die when vast tracts of land are flooded for long periods.

While the meat can be used immediately for distribution among the

affected population, or salted for later distribution, in the long run it results

in food and economic shortfalls. The effect of disasters on the biological

utilization of food, that is, intestinal absorption and subsequent utilization

of nutrients, is indirect, and dependent on factors such as the impact of

the disaster on the environment, particularly on water supply and

sanitation. This is an issue of concern, particularly in regard to

gastrointestinal infections since they affect the absorption of nutrients.

Food Science and Applied Nutrition 3

Other infectious diseases increase the demand for nutrients. These

effects are more likely to occur among the young and vulnerable groups.

If there is an increase in undernutrition rates among young children soon

after a disaster, it will most likely be the effect of gastrointestinal illness

rather than actual food shortages. This is something to keep in mind in

the implementation of surveillance mechanisms. Outbreaks of infectious

diseases are uncommon after natural disasters, especially in the Americas.

POSSIBLE ADVERSE EFFECTS OF

LARGE-SCALE FOOD DISTRIBUTION

The decision to distribute large amounts of food, although made at

the political level, should be based on the most accurate information

available. If unnecessarily large quantities of food are brought into an area,

this may hinder recovery. Food distribution requires transport and

personnel that may be better employed in other ways, and small farmers

may face hardship due to depressed market prices. Perhaps the most

serious side effect is that maintaining a population by free food

distribution, if not accompanied by essentials such as seeds and tools

needed to restart the local economy, may create dependence on relief.

SETTING PRIORITIES

The priorities in alleviating food problems are to:

• Supply food immediately where there appears to be an urgent

need, namely to isolated populations, institutions, and relief

workers;

• Make an initial estimate of likely food needs in the area, so that

steps can be taken towards procurement, transport, storage, and

distribution;

• Locate or procure stocks of food and assess their fitness for local

consumption; and

• Monitor information on food needs so that procurement,

distribution, and other programmes can be modified as the situation

changes.

IMMEDIATE RELIEF

During the first, usually chaotic, days after a disaster strikes, the exact

extent of the damage is unknown, communications are difficult, and the

number of people affected seems to double by the hour. Food distribution

must start as soon as possible to keep people fed, rather than prevent

clinical malnutrition. Given the large variety and small stocks of

commodities sent in as aid by governments, agencies, private

organizations, and individuals, however, food distribution is initially a

dayto- day exercise. Planning nutritionally sensible food rations during

4 Food Science and Applied Nutrition

this period is impossible. What matters during this “chaotic stage” is to

provide a minimum of 6.7 to 8.4 Megajoules (1,600 to 2,000 kcal) per day,

per person. As an immediate relief step, available food should be

distributed in sufficient quantity to any group that is at high risk or appears

to be wanting, to ensure survival for one week (3 or 4 kg per person). Food

may be included automatically, for example, in supplies sent to

communities isolated by earthquake or displaced by flooding. Where fuel

shortages are likely, it may be better to distribute cooked food such as

boiled rice or bread rather than dry food. No detailed calculations need

be made of the precise vitamin, mineral, or protein content of the food

distributed in the initial phase, but supplies should be acceptable and

palatable.

The most important thing to be provided is sufficient energy. If no

other items can be obtained, distribution of a cereal alone will be sufficient

to meet basic nutritional requirements. When a population can find some

of its own food, it may be possible to supply only part of the ration, or one

food item that complements the basic or staple food lacking in their

available supplies.

ESTIMATING FOOD REQUIREMENTS

As soon as possible after a disaster, a rapid assessment of the food

and nutrition situation should be made to get a rough estimate of likely

bulk food items needed. This is based on the population affected, its

composition, distribution (for example, isolated villages, refugee camps),

and locally available foods. This will enable managers to take the necessary

steps to locate and procure stocks, storage, and transport. Hoarding is not

uncommon and leads to over-response.

In the absence of detailed information, an estimate of food requirements must

be based to some extent on judgment in the light of the initial assessment, but it

should take into account the following factors:

• The probable effect of the disaster on food availability (e.g., a

tsunami may have destroyed all household supplies);

• The approximate size of the population affected;

• Normal food supply and variations within the area (e.g., the

approximate percentages of the population who are subsistence

farmers and those who depend wholly on purchased food); and

• The impact of seasonal factors. In subsistence areas just before the

harvest, for instance, household and traders’ stocks may be depleted

and the population may be more dependent on the market.

The nutrition officer should prepare estimates of foods on the basis

of a family unit (usually considered to consist of five people) for one week

and one month. Logistically, food distribution on a family basis for one

month may be considered the most practical approach. The nutrition officer

Food Science and Applied Nutrition 5

also should prepare estimates of commodities required by large population

groups, for instance, on the basis of 1,000 people for one month.

Two simple and useful rules of thumb are:

1. 16 metric tons of food sustain 1,000 people for one month, and

2. To store one metric ton of food, about two cubic metres of space

are needed.

Proper storage is extremely important to avoid food losses due to rain,

pests, or looting.

When calculating the composition of daily rations, the following points should

be kept in mind:

• The ration should be kept as simple as possible;

• To facilitate storage and distribution, nonperishable food

commodities that are not bulky should be chosen; and

• Substitution of items within food groups should be allowed for.

The food ration should be based on three food groups: a staple,

preferably a cereal; a concentrated energy source such as a fat; and a

concentrated source of protein, such as salted or dried fish or meat. In

practice, the diets will be dictated by the availability of ingredients. A

standardized ration may be impractical as availability will change daily

and according to areas. Whenever possible, vulnerable groups should

receive a food supplement in addition to the basic diet. Among these

groups we include children under 5 years old, who are growing very fast

and may suffer permanent damage if malnourished, and pregnant and

lactating women, who require more nutrients. Breastmilk is the best food

for infants under six months of age, and Health Disaster Coordinators

should not allow the emergency situation to become an excuse for flooding

the country with infant formula.

PROCUREMENT

If the calculated amount of food required exceeds immediate local

availability, and if it is anticipated that food will have to be distributed for

several months, steps must be taken to obtain food from elsewhere in the

country or abroad. A rough estimate of local food transport requirements

should also be made for this contingency.

Food for the initial emergency distribution phase should be obtained

from national government or wholesaler stocks, or from bilateral or

international development agencies (e.g., World Food Programme, NGOs).

If large quantities of food are required from abroad, procurement and

shipping may require several months.

Approaches to suitable agencies should hence be made at the earliest

possible date. It is critical that Health Disaster Coordinators advise

potential donors of the eating habits and preferences of their populations.

Food not eaten is of no nutritional benefit.

6 Food Science and Applied Nutrition

The need for special infant foods (“baby foods”) immediately after

disasters is often exaggerated. Improving maternal nutrition and assisting

mothers economically is more cost-effective and safer than airlifting

strained baby foods. Since vitamin requirements are of little concern during

the acute emergency phase after sudden-impact natural disasters,

multivitamin tablets should not be requested as a separate relief item. The

population’s specific vitamin and mineral needs will have to be assessed

for the long-term.

SURVEILLANCE

If long-term food supply problems seem likely, as in areas with

subsistence agriculture and poor communications, the nutritional status

of the community should be monitored. This can be accomplished by

making regular physical measurements of a suitable sample of the

population. Since young children are the most sensitive to nutritional

changes, the surveillance system should be based on them, remembering

that the most serious malnutrition results from an acute exacerbation of

chronic under-nutrition.

In emergency situations, weight-for-height will provide the best

indicator of acute changes in nutritional status. If height and weight cannot

be measured, arm circumference, which is simple and easy to measure,

may be used to gauge changes in communities. As the results of the first

needs assessments become available, more accurate information will make

it possible to adjust preliminary estimates of the proportion of the

population most in need of long-term food distribution.

Surveys of need should make sure to cover not only food availability,

but also identify areas where problems of labour, tools, marketing, and

other variables affecting distribution have arisen. As soon as an area is

able to return to normal consumption patterns, distribution should be

phased out.

Food Science and Applied Nutrition 7

2

Essentials of Basic Nutrition

Nutrition science investigates the metabolic and physiological

responses of the body to diet. With advances in the fields of molecular

biology, biochemistry, and genetics, the study of nutrition is increasingly

concerned with metabolism and metabolic pathways: the sequences of

biochemical steps through which substances in living things change from

one form to another.

Nitrogen is needed by animals to build proteins. Carnivore and

herbivore diets vary in their source of nitrogen, which is a limiting nutrient

for both. Herbivores consume plants to get nitrogen and carnivores

consume other animals to obtain nitrogen. Nitrogen is a common element

in the atmosphere but exists in a state that is not usable by most living

organisms, certain fungi and bacteria are able to convert atmospheric

nitrogen into a form plants can adsorb and utilize.

The human body contains chemical compounds, such as water,

carbohydrates (sugar, starch, and fibre), amino acids (in proteins), fatty

acids (in lipids), and nucleic acids (DNA and RNA). These compounds in

turn consist of elements such as carbon, hydrogen, oxygen, nitrogen,

phosphorus, calcium, iron, zinc, magnesium, manganese, and so on. All

of these chemical compounds and elements occur in various forms and

combinations (e.g., hormones, vitamins, phospholipids, hydroxyapatite),

both in the human body and in the plant and animal organisms that

humans eat. The human body consists of elements and compounds

ingested, digested, absorbed, and circulated through the bloodstream to

feed the cells of the body. Except in the unborn foetus, which receive

8 Food Science and Applied Nutrition

processed nutrients from the mother, the digestive system is the first

system involved in breaking down food prior to further digestion.

Digestive juices, excreted into the lumen of the gastrointestinal tract,

break chemical bonds in ingested molecules, and modulate their

conformations and energy states. Though some molecules are absorbed

into the bloodstream unchanged, digestive processes release them from

the matrix of foods. Unabsorbed matter, along with some waste products

of metabolism, is eliminated from the body in the feces. Studies of

nutritional status must take into account the state of the body before and

after experiments, as well as the chemical composition of the whole diet

and of all material excreted and eliminated from the body (in urine and

foeces).

Comparing the food to the waste can help determine the specific

compounds and elements absorbed and metabolized in the body. The

effects of nutrients may only be discernible over an extended period,

during which all food and waste must be analysed. The number of

variables involved in such experiments is high, making nutritional studies

time-consuming and expensive, which explains why the science of human

nutrition is still slowly evolving. In general, eating a wide variety of fresh,

whole (unprocessed), foods has proven favourable for one’s health

compared to monotonous diets based on processed foods. In particular,

the consumption of whole-plant foods slows digestion and allows better

absorption, and a more favourable balance of essential nutrients per

Calorie, resulting in better management of cell growth, maintenance, and

mitosis (cell division), as well as better regulation of appetite and blood

sugar. Regularly scheduled meals (every few hours) have also proven more

wholesome than infrequent or haphazard ones, although a recent study

has also linked more frequent meals with a higher risk of colon cancer in

men.

There are six major classes of nutrients: carbohydrates, fats, minerals,

protein, vitamins, and water. These nutrient classes can be categorized as

either macronutrients (needed in relatively large amounts) or

micronutrients (needed in smaller quantities). The macronutrients include

carbohydrates, fats, protein, and water. The micronutrients are minerals

and vitamins. The macronutrients (excluding water) provide structural

material (amino acids from which proteins are built, and lipids from which

cell membranes and some signaling molecules are built), energy.

Some of the structural material can be used to generate energy

internally, and in either case it is measured in Joules or kilocalories (often

called “Calories” and written with a capital C to distinguish them from

little ‘c’ calories). Carbohydrates and proteins provide 17 kJ approximately

(4 kcal) of energy per gram, while fats provide 37 kJ (9 kcal) per gm., though

the net energy from either depends on such factors as absorption and

digestive effort, which vary substantially from instance to instance.